How to only texture paint one side of mesh?
this is a go around that I just found.
For that you need to modify your material so it applies one different shader on each side of your faces.
So here is the mesh, the top half show back of the faces and the bottom half show the front of the faces.



And here is the material I used.



The trick is done by the geometry node setting the Backfacing attribute as factor for the two shaders.



So I hope it helps.